The removal of sulfur compounds and particularly chemically-combined sulfur, such as organosulfur compounds, from feedstreams is highly desirable for environmental concerns and in order to prevent potential catalyst deactivation as well as equipment corrosion.
Typically, hydrocarbon products contain various amounts of sulfur compounds in the form of, for example, chemically-combined sulfur, such as inorganically combined sulfur and organically combined sulfur, i.e., organosulfur compounds.
The presence of organosulfur compounds in hydrocarbon streams results naturally, as well as from the introduction of organosulfur compounds, into the hydrocarbon streams during conventional processes for producing and treating hydrocarbon products.
As previously indicated, if chemically-combined sulfur, such as organosulfur compounds, are not removed from the hydrocarbon streams, the presence of organosulfur compounds in the resultant hydrocarbon products, including natural gas, paraffins, olefins and aromatics, particularly gasoline or other fuels, can cause corrosion of processing equipment and engine parts, as well as other deleterious effects, particularly when water is present.
U.S. Pat. No. 4,283,373, FRECH et al., is directed to a method of removing sulfur compounds from a gas stream by contacting the stream with alkali metal salts of sulfonamides. The preferred sulfonamide disclosed is chloramine-T which can be sprayed into the gas stream, or the gas can be passed through a porous carrier impregnated with the chloramine, or through a resin with pendant substituted sulfonamide groups.
The information disclosed by FRECH et al. as background for sulfur removal include the following:
U.S. Pat. No. 1,783,901 relates to removing H.sub.2 S from natural gas depending upon the reactivity of the H.sub.2 S with amino nitrogen.
U.S. Pat. No. 4,035,474, KUNKEL et al., is directed to a method for removal of sulfur from tail gas by use of a cold bed absorption process which utilizes a catalyst.
U.S. Pat. No. 3,756,976, URANECK et al., removes thiol odor from polymer latex through the use of numerous compounds that convert odiferous sulfur compounds to non-odiferous form, i.e., the use of alkali metal salts of N-halogenated arylsulfonamides.
U.S. Pat. No. 3,306,945, CONVISER, is directed to a process for purifying liquid unsaturated hydrocarbons of by removing impurities using molecular sieve materials. CONVISER discloses that sulfides (R--S--R), which include dialkyl sulfides, may be adsorbed by zeolitic molecular sieves material having sufficiently large pores to such impurities, such as the synthetic type X.
U.S. Pat. No. 4,592,892, EBERLY, Jr., is directed to a process of using a sorbent catalyst to remove sulfur from naphtha. The sulfur impurities which are disclosed as being removed are mercaptans, thiophenes, disulfides, thioethers, hydrogen sulfide, carbonyl sulfide, and the like; and the adsorbent is disclosed as a Group VI B and/or Group VIII metal catalyst, for example, cobalt molybdate or nickel molybdate supported on alumina.
U.S. Pat. No. 3,367,862, MASON et al., is directed to a process for desulphurizing heavy residual fractions by contacting with water in the presence of the catalyst comprising the metal, metal oxide, or metal sulfide, distended on a charred base.
Naphthas, which are used for reforming, typically contain between 50 wppm to 500 wppm sulfur as mercaptans, such as 2-propyl mercaptan, butyl mercaptan, and thiophene, hindered thiophenes, such as 2, 5-dimethylthiophene. Accordingly, naphthas for reforming are usually treated with hydrogen over a hydrotreating catalyst, such as a sulfided cobalt and molybdenum on alumina support, or nickel and molybdenum on alumina support, to protect reforming catalysts. Hydrotreating converts sulfur compounds to hydrogen sulfide, decomposes nitrogen and oxygen compounds and saturates olefins. Hydrotreating is done at a temperature between about 400.degree. F. and 900.degree. F., a pressure between 200 psig and 750 psig, liquid hourly space velocity between 1 and 5, and hydrogen circulation rate of 500 to 3000 scf/hr. Modern hydrotreating processes can reduce sulfur concentration in naphtha to 0.25 wppm and even to 0.1 wppm.
U.S. Pat. No. 3,898,153 is directed to purifying reformer feedstreams by passing hydrotreated reformer feedstock through a zinc oxide bed.
U.S. Pat. No. 4,634,518 passes hydrotreated reformer feed over massive nickel catalysts.
Other treatments for purifying hydrotreated feedstock for reforming are disclosed in U.S. Pat. Nos. 4,320,220; 4,225,417; 4,575,415; and 4,534,943; wherein the disclosed treatment is over manganese oxides.
A suitable manganese oxide formulation for this purpose which is commercially available is Sulfur Guard HRD-264 sold by Englehard wherein recommended treatment conditions are temperatures within the range of 600.degree. F. to 1000.degree. F., pressures within the range of about 150 psig to 700 psig, 1/1 to 30/1 hydrogen to oil molar ratio, and 500 to 50,000 ghsv.
U.S. Pat. No. 4,456,527 is directed to purifying hydrotreated feed for reforming over zeolite L catalysts.
German Patent No. 3 527 110-A, CIBA GEIGY AG, is directed to removing hydrogen sulfide from gases by oxidation using a solution containing anthraquinone sulphonamide and variable valency metal compounds followed by reoxidation, preferably using oxygen of hydroquinone.
The process is disclosed as being useful to purify gas, town gas, waste gases, and CO.sub.2 rich streams from coal combustion, wherein the impurities which may be present are identified as including certain oxides of C, N and S, H.sub.2, organic S compounds, and HCN.
British Patent No. 2 209 386, CIBA GEIGY AG, is directed to the removal of hydrogen sulphide from gases or liquid hydrocarbons by washing with alkaline solution containing anthraquinone disulphonamides. It is disclosed that hydrogen sulfide in gases is adsorbed, for subsequent removal in sulfur, by washing the gas with an aqueous alkaline solution of one or more anthraquinone sulphonamides.
European Application No. 74 894, CIE FRANCAISE RAFFINAGE, is directed to the extraction of hydrogen sulfide, carbon dioxide and the like, from hydrocarbon gases using sulphonamide or sulphamide as solvent. It is disclosed that undesirable gases, for example, H.sub.2 S, CO.sub.2, COS, and mercaptans, are removed from their mixtures with hydrocarbons and/or H.sub.2 by a solvent whose molecule contains at least one group N--SO.sub.2, and preferably a sulphonamide or sulphamide.